Whether or not photosynthesis relies on superposition is still an open question. However, the more we learn, the more it seems processes we take for granted are not possible without quantum phenomena. For example, the Sun isn’t hot enough to create light and only does so with quantum tunneling, which also helps explain how DNA mutates and enzymes function. Even birds can’t navigate without quantum entanglement. All of these are just a handful of other examples emerging from the rising field of quantum biology, so it may not be as crazy as it seems.
The Happy Neuron
Which all goes to show that we do not understand physics. It drives me crazy when someone argues that X cannot be possible because physics says so. We really don't know enough to be certain of much. We can assert probabiliies, but that's about the limit of our understanding. We should say that X is highly unlikely.
Maybe we will progress beyond that, maybe not.